Synergistic weed control from applications of pyridine carboxylic acid herbicides and photosystem II inhibitors

Abstract

Disclosed herein are herbicidal compositions comprising a herbicidally effective amount of (a) a pyridine carboxylic acid herbicide or an agriculturally acceptable N-oxide, salt, or ester thereof, and (b) a photosystem II inhibitor, or an agriculturally acceptable salt or ester thereof. Also disclosed herein are methods of controlling undesirable vegetation which comprise applying to vegetation or an area adjacent the vegetation or applying to soil or water to prevent the emergence or growth of vegetation (a) a pyridine carboxylic acid herbicide or an agriculturally acceptable N-oxide, salt, or ester thereof, and (b) a photosystem II inhibitor, or an agriculturally acceptable salt or ester thereof, wherein (a) and (b) are each added in an amount sufficient to provide a herbicidal effect.

What is claimed is: 
     
       1. A herbicidal composition comprising a herbicidally effective amount of
 (a) a pyridine carboxylic acid herbicide or an agriculturally acceptable N-oxide, salt, or ester thereof, and 
 (b) a photosystem II inhibitor selected from the group consisting of bromoxynil, bentazon, isoproturon, metribuzin, atrazine, agriculturally acceptable salts and esters thereof, and combinations thereof, 
 wherein (a) and (b) are provided in a weight ratio of (a) in grams acid equivalent to (b) in grams active ingredient of from 1:90 to 1:5, and 
 wherein the pyridine carboxylic acid herbicide comprises a compound defined by the formula below 
 
       
         
           
           
               
               
           
         
         wherein R 1′  is hydrogen, or substituted or unsubstituted C 7 -C 10  arylalkyl; 
         or an agriculturally acceptable N-oxide or salt thereof. 
       
     
     
       2. The composition of  claim 1 , wherein the pyridine carboxylic acid herbicide comprises one of the following: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
       3. The composition of  claim 1 , wherein the pyridine carboxylic acid herbicide comprises 
       
         
           
           
               
               
           
         
       
     
     
       4. The composition of  claim 1 , wherein (b) is bromoxynil or an agriculturally acceptable salt or ester thereof. 
     
     
       5. The composition of  claim 1 , wherein (b) is isoproturon. 
     
     
       6. The composition of  claim 1 , wherein (b) is metribuzin or an agriculturally acceptable salt thereof. 
     
     
       7. The composition of  claim 1 , further comprising an agriculturally acceptable adjuvant or carrier. 
     
     
       8. The composition of  claim 1 , further comprising an additional pesticide. 
     
     
       9. The composition of  claim 1 , wherein the active ingredients in the composition consist of (a) and (b). 
     
     
       10. The composition of  claim 1 , which wherein the composition is provided as a herbicidal concentrate. 
     
     
       11. The composition of  claim 1 , wherein R 1′  is hydrogen. 
     
     
       12. The composition of  claim 1 , wherein R 1′  is a substituted or unsubstituted C 8  arylalkyl group. 
     
     
       13. The composition of  claim 1 , wherein R 1′  is a benzyl group. 
     
     
       14. A method of controlling undesirable vegetation comprising applying to vegetation or an area adjacent the vegetation or applying to soil or water to control the emergence or growth of vegetation a herbicidally effective amount of the composition of  claim 1 . 
     
     
       15. The method of  claim 14 , wherein (a) and (b) are applied post-emergence to the undesirable vegetation. 
     
     
       16. The method of  claim 14 , wherein (a) is applied in amount of from 0.1 g ae/ha to 300 g ae/ha. 
     
     
       17. The method of  claim 14 , wherein (b) is applied in amount of from 5 g ai/ha to 4000 g ai/ha. 
     
     
       18. The method of  claim 14 , further comprising applying an additional pesticide. 
     
     
       19. The method of  claim 14 , wherein the undesirable vegetation includes a broadleaf weed. 
     
     
       20. The method of  claim 14 , wherein the undesirable vegetation comprises a herbicide resistant or tolerant weed. 
     
     
       21. The method of  claim 14 , wherein the undesirable vegetation includes velvetleaf, pigweed, rape, thistle, nutsedge, large crabgrass, barnyardgrass, poinsettia, common sunflower, ivyleaf morningglory, wild pansy, ivy-leaved speedwell, or a combination thereof. 
     
     
       22. The method of  claim 14 , wherein the active ingredients applied to the vegetation or an area adjacent the vegetation or applied to soil or water to control the emergence or growth of vegetation consist of (a) and (b).